Multiple use disposable injection pen

ABSTRACT

A medication injection pen, including a housing, a dose set knob (DSK) comprising an internal thread and an internal key proximate to a distal end of the internal thread, and a dose stop member comprising an external thread engaging the internal thread of the dose set knob. Rotation of the dose set knob to set a medication dose causes lateral translation of the dose stop member with respect to the dose set knob, and when the dose set knob is rotated to a last dose setting position, the dose stop member rotationally abuts the internal key thereby preventing further rotational movement of the dose set knob in a dose setting direction.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Nonprovisional patentapplication Ser. No. 14/640,431, filed on Mar. 6, 2015, which is acontinuation of U.S. Nonprovisional patent application Ser. No.14/005,222, filed on Sep. 13, 2013, which is the U.S. National Stage ofInternational Patent Application No. PCT/US2012/029308, filed on Mar.15, 2012, which claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application Ser. No. 61/457,391, filed on Mar. 16,2011. Each of the above applications is hereby incorporated by referencein its entirety.

FIELD OF THE INVENTION

The invention relates to a multiple use pen-type injection device withimproved functionality, including improved dial back of a set dose, andimproved last dose control to prevent a dose from being set that islarger than the amount of drug remaining in a medication cartridge.

BACKGROUND OF THE INVENTION

Various medication injection pen devices are known in the prior art.These prior art devices sometimes include features for enabling a userto correct a dose that has been set too large, which may be referred toas “dial back”. Another feature that may be provided by some of theprior art devices is the ability to control a last dose of a medicationcartridge such that a user cannot set a dose greater than the remainingamount of medication in the cartridge. This feature is referred to aslast dose control or last dose management. Both of these features aredesired by users of such pen devices; however, the prior art devices donot satisfactorily meet these needs. Many prior art devices may provideone of these features, but not both. Further, many of the prior artdevices require additional steps for performing dial back, which arecumbersome and not intuitive to the user. Thus, there is a need in theart to provide improved functionality of dial back and last dose controlmechanisms together in a medication injection pen.

SUMMARY OF EMBODIMENTS OF THE INVENTION

Exemplary embodiments of the present invention address at least theabove problems and/or disadvantages and provide at least the advantagesdescribed below.

In accordance with an exemplary embodiment of the present invention, amedication injection pen includes a housing and a dose set knob havingat least one internal tooth. A brake member has a plurality of axiallyextending splines. A driver includes at least one external toothengaging the at least one internal tooth of the dose set knob and atleast one ratchet arm engaging the plurality of axially extendingsplines. The driver is prevented from rotating with respect to the doseset knob while moving axially with the dose set knob during dose settingand dose correcting, and the driver rotates with the dose set knobduring an injection.

In accordance with another exemplary embodiment of the presentinvention, a medication injection pen includes a housing and a dose setknob for setting and correcting a dose. A brake member is axially androtationally fixed to the housing. A driver moves axially with the doseset knob when setting and correcting the dose, and moves rotationallywith the dose set knob when injecting the set dose. A hollow piston rodmoves axially when injecting the set dose. A brake core member isdisposed within the hollow piston rod to substantially preventrotational movement of the hollow piston rod.

In accordance with another exemplary embodiment of the presentinvention, a medication injection pen includes a housing, a dose setknob (DSK) comprising an internal thread and an internal key proximateto a distal end of the internal thread, and a dose stop membercomprising an external thread engaging the internal thread of the doseset knob. Rotation of the dose set knob to set a medication dose causeslateral translation of the dose stop member with respect to the dose setknob, and when the dose set knob is rotated to a last dose settingposition, the dose stop member rotationally abuts the internal keythereby preventing further rotational movement of the dose set knob in adose setting direction.

Optionally, in medication injection pen according to any of theembodiments of the present disclosure a distal end of said internalthread terminates at the internal key of the DSK.

Optionally, in medication injection pen according to any of theembodiments of the present disclosure a distal end of said internalthread terminates at a distance from the internal key of the DSK.

Optionally, in medication injection pen according to any of theembodiments of the present disclosure, the dose knob comprises a cut outextending from a distal end of the internal thread of the DSK to aproximal end of the internal key of the DSK.

Optionally, in medication injection pen according to any of theembodiments of the present disclosure where the dose knob comprises acut out extending from a distal end of the internal thread of the DSK toa proximal end of the internal key of the DSK, the distal end of theinternal thread comprises a planer sharp razer-edge feathering of thethread form.

Optionally, in medication injection pen according to any of theembodiments of the present disclosure, the internal key of the DSK ispoisoned such that when the dose stop member reaches a maximum dosecondition dialable by the DSK, a distal end of the dose stop memberimpinges on a proximal end face of the internal key, with the distal endof the dose stop member approaching the proximal end face of theinternal key on a helical path dictated by the internal thread of theDSK.

Additional objects, advantages and salient features of exemplaryembodiments of the invention will become apparent to those skilled inthe art from the following detailed description, which, taken inconjunction with annexed drawings, discloses exemplary embodiments ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other exemplary features and advantages of certainexemplary embodiments of the present invention will become more apparentfrom the following description of certain exemplary embodiments thereofwhen taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a first exemplary embodiment of aninjection pen according to the present invention;

FIG. 2A is a perspective view of the injection pen of FIG. 1 with alower pen body removed;

FIG. 2B is an exploded assembly view of the injection pen of FIG. 1;

FIG. 2C is a partial cut-away perspective view of the pen upper body ofFIG. 2B;

FIG. 3 is an elevational view in cross-section of the injection pen ofFIG. 2A;

FIG. 4 is a perspective view of a dose set knob of FIG. 3;

FIG. 5 is a side perspective view of a setback member of FIG. 3;

FIG. 6 is a perspective view of a brake tower of FIG. 3;

FIG. 7 is a perspective view of the engagement between the brake towerand the setback member;

FIG. 8 is a perspective view of a lead screw of FIG. 3;

FIG. 9 is a front perspective view of the setback member of FIG. 5;

FIG. 10 is a perspective view of the engagement between the setbackmember, the brake tower and a lead screw of FIG. 3;

FIG. 11 is an elevational view in cross-section of the engagementbetween the dose setting knob, lead screw, setback member and braketower;

FIG. 12 is an elevational view in cross-section of the dose setting knoband setback member relative to the lead screw and brake tower aftersetting a dose;

FIG. 13 is a perspective view of a dose stop member engaging the setbackmember of FIG. 3;

FIG. 14 is an elevational view in cross-section of the dose settingknob;

FIG. 15 is an elevational view in cross-section of the dose stop memberin an initial position;

FIG. 16 is a partial elevational view in cross-section of the dose stopmember in a final position;

FIG. 17 is an elevational view of an indicator window disposed in anupper body portion of the injection pen of FIG. 1;

FIG. 18 is an elevational view of the indicator window of FIG. 17indicating that a set dose has not been fully injected;

FIG. 19 is a perspective view of the dose set knob including anindicator;

FIG. 20 is an exploded assembly view of an injection pen according to asecond exemplary embodiment of the present invention;

FIG. 21 is an elevational view in cross-section of the injection pen ofFIG. 20;

FIG. 22 is an exploded assembly view of an injection pen according to athird exemplary embodiment of the present invention;

FIG. 23 is an elevational view in cross-section of the injection pen ofFIG. 22;

FIG. 24 is a perspective view of a brake tower core and a brake tower ofFIG. 22;

FIG. 25 is a perspective view of the engagement between the brake towercore and a piston rod of FIG. 22;

FIG. 26 is a perspective view of a piston rod;

FIG. 27 is a perspective view of the engagement between the brake towercore and the piston rod of FIG. 22;

FIG. 28 is an elevational view in cross-section of the engagementbetween the brake tower core and a lead screw of FIG. 22;

FIG. 29 is a perspective view of an injection pen according to a fourthexemplary embodiment of the present invention;

FIG. 30 is an exploded assembly view of the injection pen of FIG. 29;

FIG. 31 is a perspective view of a brake tower of FIG. 30;

FIG. 32 is a perspective view of a brake tower core of FIG. 30;

FIG. 33 is a perspective view of a lead screw of FIG. 30;

FIG. 34 is a perspective view of a piston rod of FIG. 30;

FIG. 35 is an elevational view in cross-section of the injection pen ofFIG. 29;

FIG. 36 is an elevational view in cross-section of the engagementbetween the the brake tower, brake tower core, lead screw and piston rodof FIG. 30;

FIG. 37 is an elevational view in cross-section of a piston rod of FIG.30;

FIG. 38 is a perspective view of a piston rod in accordance with a fifthexemplary embodiment of the present invention;

FIG. 39 is a perspective view of a brake tower core in accordance withthe fifth exemplary embodiment of the present invention;

FIG. 40 is a perspective view of the engagement between the piston rodand brake tower core of FIGS. 38 and 39;

FIG. 41 is an elevational view in cross-section of an injection pen inaccordance with the fifth exemplary embodiment of the present invention;

FIG. 42 is an elevational view in cross-section of an injection pen inaccordance with a sixth exemplary embodiment of the present invention;

FIG. 43 is a perspective view of a lead screw of FIG. 42;

FIG. 44 is an elevational view in cross-section of the lead screw ofFIG. 43;

FIG. 45 is an elevational view in cross-section of the engagementbetween the brake tower core and lead screw of FIG. 42;

FIG. 46 is an elevational view in cross-section of the brake tower coreand lead screw assembly being inserted in a brake tower of FIG. 42;

FIG. 47 is an elevational view in cross-section of the lead screw priorto forming a snap connection with the brake tower;

FIG. 48 is an enlarged elevational view in cross-section of the leadscrew prior to forming the snap connection with the brake tower;

FIG. 49 is an elevational view in cross-section of a snap-connectionbetween the lead screw and the brake tower;

FIG. 50 is an elevational view in cross-section of a piston rod insertedin the brake tower assembly of FIG. 49;

FIG. 51 is an end elevational view of the brake tower assembly of FIG.50;

FIG. 52 is a exploded assembly view of an injection pen in accordancewith a seventh exemplary embodiment of the present invention;

FIG. 53 is an elevational view in cross-section of the injection pen ofFIG. 52;

FIG. 54 is a perspective view of a dose set knob of the injection pen ofFIG. 52;

FIG. 55 is an elevational view in cross-section of the injection pen ofFIG. 54;

FIG. 56 is a perspective view of a setback member of the injection penof FIG. 52;

FIG. 57 is an elevational view in cross-section of the setback member ofFIG. 56;

FIG. 58 is a distal perspective view of the setback member of FIG. 56;

FIG. 59 is a perspective view of a lead screw of the injection pen ofFIG. 52;

FIG. 60 is a perspective view of a brake tower core of the injection penof FIG. 52;

FIG. 61 is a perspective view of a brake tower of the injection pen ofFIG. 52;

FIG. 62 is an elevational view in cross-section of the brake tower ofFIG. 61;

FIG. 63 is a perspective view of a piston rod of the injection pen ofFIG. 52;

FIG. 64 is an elevational view in cross-section of the piston rod ofFIG. 63;

FIG. 65 is a perspective view of a pen upper body of the injection penof FIG. 52;

FIG. 66 is an elevational view in cross-section of the pen upper body ofFIG. 65;

FIG. 67 is a perspective view of a clicker body of the injection pen ofFIG. 52;

FIG. 68 is a bottom plan view of the clicker body of FIG. 67;

FIG. 69 is an elevational view of the clicker body of FIG. 67;

FIG. 70 is a top plan view of the clicker body of FIG. 67;

FIG. 71 is a proximal perspective view of the brake tower of theinjection pen of FIG. 52;

FIG. 72 is a perspective view of the lead screw and brake tower coreprior to engagement with the brake tower of the injection pen of FIG.52;

FIG. 73 is a perspective view of the lead screw connected to the braketower core prior to being connected to the brake tower of FIG. 72;

FIG. 74 is an elevational view of the lead screw and brake tower coreconnected to the brake tower of FIG. 72;

FIG. 75 is an elevational view of the engagement between the piston rodand brake tower core of the injection pen of FIG. 52;

FIG. 76 is an elevational view in cross-section of a clicker bodydisposed between a dose set knob and a setback member of an injectionpen in accordance with an eighth exemplary embodiment of the presentinvention;

FIG. 77 is a perspective view of the clicker body of FIG. 76;

FIG. 78 is partial perspective view of the setback member of theinjection pen of FIG. 76;

FIG. 79 is a partial perspective view of the dose set knob of theinjection pen of FIG. 76;

FIG. 80 is an elevational view in cross-section of the injection pen ofFIG. 76.

FIG. 81 is an elevational partial detailed view in cross-section of adose setting knob according to an embodiment of the present disclosureas shown in FIG. 55;

FIG. 82A is a volumetric cross-sectional view of the dose setting knobof FIG. 81;

FIG. 82B is a three-dimensional view of the dose setting knob of FIG.82A;

FIG. 83A is an elevational view in cross-section of a dose setting knobaccording to another embodiment of the present disclosure;

FIGS. 83B and 83C are elevational views in cross-section of a dosesetting knob according to an embodiment of the present disclosure asshown in FIG. 83A with a dose stop member;

FIG. 83D is a three-dimensional view of the dose setting knob of FIGS.83A, 83B, 83C, 84A, 84B, and 84C.

FIG. 84A is an elevational view in cross-section of a dose setting knobaccording to yet another embodiment of the present disclosure; and

FIGS. 84B and 84C are elevational views in cross-section of a dosesetting knob according to an embodiment of the present disclosure asshown in FIG. 84A with a dose stop member.

Throughout the drawings, like reference numerals will be understood torefer to like elements, features and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The matters exemplified in this description are provided to assist in acomprehensive understanding of exemplary embodiments of the inventionwith reference to the accompanying drawing figures. Accordingly, thoseof ordinary skill in the art will recognize that various changes andmodifications of the exemplary embodiments described herein can be madewithout departing from the scope and spirit of the claimed invention.Also, descriptions of well-known functions and constructions are omittedfor clarity and conciseness.

FIG. 1 depicts a view of an injection pen 51 according to a firstexemplary embodiment of the present invention. As shown, the injectionpen 51 includes an pen upper body or housing 1, which houses a pluralityof dose setting and injection components. The pen upper body 1 isconnected to a cartridge housing 14, which houses a medication cartridge15, as shown in FIGS. 2A and 2B. The injection pen 51 may also include alower pen cap 12 to cover the cartridge 15 and cartridge housing 14 whenthe injection pen is not in use. As shown, the injection pen 51 includesa dose set knob 2 that includes a knob-like portion that is rotated by auser to set a desired dose. The dose set knob 2 also includes aplurality of numerals, as shown in FIG. 2B, corresponding to a number ofdosage units that is visible through a window 13 provided on the penupper body 1. A user rotates the dose set knob 2 until the desired doseis visible in the window 13. The pen upper body 1 may include an arrowor other indicator 53 to precisely indicate the set dose. Once thedesired dose is set, a user presses the button 3 until the set dosageamount is completely injected. An outer shield 69 (FIG. 2b ) can cover aneedle 56 to prevent accidental needle sticks upon removal of the lowerpen cap 12.

Optionally, the pen upper body 1 can also include a second window 55 forindicating when the set dose is complete, as shown in FIGS. 1, 2A and2B. An indicator or marker 27, as shown in FIG. 19, can be provided onthe outer surface of the dose set knob 2 that is visible through thesecond window 55 only when the dose set knob 2 has returned to itsinitial position, thus indicating that the injection process iscomplete. FIG. 18 depicts a scenario when the dose set knob 2 has almostreturned to its initial position. As shown, the indicator 27 is notvisible through the window 55, thus the user is notified that theinjection is not complete. Once the marker 27 is visible in window 55,as shown in FIG. 17, the user is assured that the set dose was fullyinjected.

FIG. 3 depicts a cross-section of an injection pen 51 in accordance withthe first exemplary embodiment of the present invention. Reference tothe individual components may be better understood in view of theexploded assembly view shown in FIG. 2B. As shown, a push button 3 isprovided at a proximal end, closest to a user and farthest from a needle56, of the pen upper body 1. The push button 3 preferably comprises anannular bead or rim 57 that engages with a corresponding annular groove58 provided on the internal surface of the dose set knob 2. The annularrim and groove connection is preferably a friction fit that maintainsthe push button 3 in a biased position on the dose set knob 2 under theforce of a button spring 10, but allows the push button 3 to be pushedinto the dose set knob 2 for injecting a set dose. The interior of thepush button 3 accommodates a setback bearing insert 8 that rests on aninternal surface at a proximal end of a setback member or driver 9. Thepush button 3 is designed to rotate freely on the setback bearing insert8.

The setback member or driver 9 is a cylindrical member, as shown in FIG.5, coaxial with and surrounded by the dose set knob 2. The setbackmember 9 is provided co-axially around a brake tower 5, as shown in FIG.6, that is axially and rotatably fixed to the pen upper body 1. Thebrake tower 5 co-axially surrounds a piston rod 6, as shown in FIG. 3.The piston rod 6 includes a set of keys 62 that engage a slot internalto the brake tower 5 to rotatably lock the piston rod 6 to the braketower 5. The piston rod 6 preferably includes a plurality of threads 64provided on the interior surface thereof, as shown in FIG. 3. The pistonrod 6 co-axially surrounds a lead screw 4 that includes a series ofthreads 42 at least at its distal end, as shown in FIG. 20. The leadscrew threads 42 are in threaded engagement with the internal threads 64provided on the piston rod 6. As discussed further below, due to itsthreaded engagement with the lead screw 4, the piston rod 6 is movedinto the cartridge 15 during injection to press on a stopper 16 providedinside the cartridge 15 to expel a dose of medication. A wave clip orspring 11, as shown in FIGS. 2B and 3, is provided between a distal endof the brake tower 5 and the cartridge 15 to bias the cartridge 15 in adistal direction to prevent any movement of the cartridge 15 duringinjection, and thus ensuring that an accurate dose is injected.

To set a dose using the injection pen 51 of the first exemplaryembodiment, a user rotates the knob portion of the dose set knob 2relative to the pen upper body 1. An outer surface 59 of the dose setknob 2 includes a thread 23, as best shown in FIG. 19, that is inthreaded engagement with a plurality of threads 17 (FIG. 2C) provided onthe internal surface of the pen upper body 1, as shown in FIG. 3.Accordingly, as the dose set knob 2 is rotated relative to the pen upperbody 1, the dose set knob 2 screws or advances a distance out of the penupper body 1, as shown in FIG. 3. The dose set knob 2 includes anannular shoulder or rim 21 on the interior surface thereof near theproximal end, as shown in FIGS. 3 and 4. This annular shoulder 21engages with an enlarged portion or head 91 of the setback member 9, asshown in FIGS. 3 and 5. The annular shoulder 21 of the dose set knob 2preferably comprises a series of teeth or ridges 22 that engage with aplurality of similarly shaped teeth or ridges 92 provided on theenlarged head 91 of the setback member 9. Preferably, the dose set knobteeth 22 and the setback member teeth 92 extend in opposite axialdirections. During dose setting, the dose set knob 2 is free to rotatewith respect to the setback member 9 in both clockwise andcounter-clockwise directions. As this occurs, the plurality of teeth orridges 22 on the dose set knob 2 slip past the teeth 92 provided on thehead portion 91 of the setback member 9, thus providing a tactile signalor clicking noise to indicate the setting of a dosage amount. As furtherdescribed below, the dose set knob 2 is enabled to rotate relative tothe setback member 9 during setting due to a one-way ratchet thatprevents the setback member 9 from rotating together with the dose setknob 2 in the setting direction.

To correct a set dose that may have been set too high, the user simplyrotates back the dose set knob 2 in the opposite direction. Rotation ofthe dose set knob 2 in this direction is not transferred to the setbackmember 9 due to the one-way ratchet between the setback member 9 and thebrake tower 5, as shown in FIG. 7. The setback member 9 near its distalend includes a pair of ratchet arms 96, as shown in FIG. 5 and FIG. 7.The pair of ratchet arms 96 engages a plurality of splines or teeth 52provided on the external surface of the brake tower 5, as shown in FIG.6 and FIG. 7. The ratchet arms 96 and splines or teeth 52 are configuredto allow relative rotation in only one direction, namely, the directionthat enables injection of a set dose. The friction provided between theratchet arms 96 and the teeth 52 on the brake tower 5 is greater thanthe friction between the corresponding teeth 92 and 22 on the setbackmember 9 and the dose set knob 2, respectively. Thus, the dose set knob9 can be rotated back to correct a set dose without causing rotation ofthe setback member 9 in this direction. Accordingly, the teeth 92 and 22provided on the setback member 9 and dose set knob 2, respectively, slippast each other to provide a clicking noise during dialing back of thedose, just as during normal dose setting, thereby indicating correctionof the set dose.

As the dose set knob 2 screws or advances axially out of the upper body1 during the setting of a dose, the setback member 9 is also caused tomove axially out of the body by a corresponding distance. This axialmovement is caused by the engagement between the annular shoulder 21 onthe dose set knob 2 pushing against the enlarged head portion 91 of thesetback member 9 during its movement out of the body. Once a desireddose is set, the user pushes the push button 3 which is coupled to thesetback bearing insert 8 that is axially connected to the setback member9. Under the force applied by the user pressing the push button 3, thesetback member 9 is moved into a locking or meshing engagement with thedose set knob 2 via a meshing of the respective teeth or ridges 92 and22 provided on the dose set knob 2 and the setback member 9,respectively. As the user continues to press the push button 3, the doseset knob 2 is caused to rotate and screw back down into the pen upperbody 1 via the thread engagement between the thread 23 on the dose setknob 2 and the thread 17 in the pen upper body 1. Rotation of the doseset knob 2 is then transferred to the setback member 9 due to theirlocking or meshed engagement. The force of the user pressing the button3 is enough to overcome the friction between the ratchet arms 96 on thesetback member 9 and the teeth or splines 52 on the brake tower 5. As aresult, the setback member 9 is enabled to rotate in this direction. Asthe setback member 9 rotates relative to the brake tower 5 duringinjection, the ratchet arms 96 produce a tactile signal or clickingnoise as they ratchet past the teeth 52 on the brake tower 5. Thisindicates to the user that injection of the set dose is taking place.

Rotation of the setback member 9, as allowed during injection, is thentransferred to the lead screw 4, which is rotatably fixed to the setbackmember 9 via a key groove connection provided between the lead screw 4and the setback member 9. As shown in FIG. 9, an internal surface 60 ofthe setback member 9 includes a groove or slot 98 that is engaged with akey 48 provided at the proximal end of the lead screw 4, as shown inFIG. 10. The setback member 9 preferably includes two oppositelydisposed slots 98 for engaging two oppositely disposed keys 48 providedon the lead screw 4. The setback member 9 moves axially relative to thelead screw 4 during dose setting and dose correcting, via the key 48 andslot 98 interconnection as shown in FIGS. 11 and 12. In one embodiment,the length of the slot 98 in the setback member 9 may be configured tocorrespond to a maximum dose to be injected in a single injection. Thelead screw 4 is axially fixed with respect to the pen upper body 1 via asnap engagement with the brake tower 5 which is axially and rotatablyfixed to the pen upper body 1 as discussed further below. As shown inFIGS. 8 and 11, the lead screw 4 includes a disk like portion 44 with anangled surface 45 that enables the lead screw 4 to snap in behind a rimor set of protrusions 54 provided on the interior of the brake tower 5,as shown, thus axially locking the lead screw 4 with respect to the penupper body 1.

As described above, the lead screw 4 includes a plurality of threads 42at its distal end that are in threaded engagement with a plurality ofthreads 64 preferably provided along the entire length of a hollowpiston rod 6 as shown in FIG. 3. The piston rod 6 is held non-rotatablewith respect to the pen upper body 1 due to a non-rotatable couplingwith the brake tower 5, which is held axially and rotatably fixed withrespect to the pen upper body 1. The piston rod 6 includes a key or setof keys 62 at its distal end that engage with a slot 61 (FIG. 12)provided on the internal surface of the brake tower 5 to preventrelative rotation therebetween while permitting the piston rod 6 to moveaxially with respect thereto. The threads 42 of the lead screw 4 have aflat portion 43 corresponding to a flat portion 65 of the piston rod 6(FIG. 2b ) such that axial movement of the lead screw during dosesetting and dose correcting does not result in axial movement of thepiston rod 6. Accordingly, rotation of the lead screw 4 during injectionof a dose causes the threads 42 of the lead screw 4 to engage thethreads 64 of the piston rod 6, thereby axially moving the piston rod 6.

During assembly, the brake tower 5 is inserted into the pen upper body 1from the distal end. As shown in FIG. 3, the pen upper body 1 includes atransverse wall 18 that limits the movement of the brake tower 5 intothe body 1 by blocking an enlarged distal portion 66 of the brake tower5, as shown. Further, an inwardly protruding key 19 is also provideddistally from the transverse wall 18 on the internal surface of the penupper body 1, as shown in FIG. 15. The key 19 engages with a slot 55provided on the enlarged distal portion 66 of the brake tower 5, asshown in FIG. 6, to rotationally fix the brake tower 5 with respect tothe pen upper body 1. Preferably, a plurality of axially extending keys19 are disposed on the inner surface of the pen upper body 1, as shownin FIG. 15, to engage a plurality of slots 55 on the enlarged distalportion 66 of the brake tower 5.

Because the piston rod 6 is non-rotatable with respect to the body 1, asthe lead screw 4 is caused to rotate during injection, as describedabove due to its rotational coupling with setback member 9, the pistonrod 6 through its threaded engagement with lead screw 4 is caused tomove in the distal direction to press against the stopper 16 provided inthe medicament cartridge 15, thus expelling a liquid medicationtherefrom. A mechanical advantage is preferably provided such that thedose set knob 2 moves further in the axial direction than the piston rod6 during the injection, reducing the injection force that must beapplied by the user. This is preferably accomplished by providingdifferent pitches for the threaded connection between the dose set knob2 and the pen upper body 1 and the threaded connection between the leadscrew 4 and the piston rod 6. The ratio between the thread pitches canvary depending on the liquid medication and the expected dose volumes.For example, the pitch ratio can be 4.35:1 or 3.25:1, but is not limitedthereto. The piston rod 6 is prevented from moving in the proximaldirection because the lead screw 4 is rotatable in only a singledirection (that which results in distal movement of the piston rod 6)due to the one-way ratchet between the setback member 9 and the braketower 5. Thus, accurate dosing can be ensured because the piston rod 6maintains its engagement with the stopper 16 between injections.

A dose stop member 7, as shown in FIGS. 2b and 13, is provided for lastdose management, to prevent the setting of a dose that is larger thanthe remaining amount of medication in the cartridge 15. The dose stopmember 7 is axially slidable but rotationally fixed with respect to thesetback member 9 by being positioned between a pair of splines 94provided on the outer surface of the setback member 9. The dose stopmember 7 is a half-nut like element, as shown, that is threaded on itsouter surface with a plurality of threads 72. These threads 72 areconfigured to engage with corresponding threads 24 provided on theinterior of the dose set knob 2, as shown in FIG. 14. FIG. 15 depictsthe dose stop member 7 in its initial position. As shown, the dose stopmember 7 is threadedly engaged with one or two of the proximal-mostthreads of threads 24 provided on the dose set knob 2. During dosesetting, as the dose set knob 2 rotates relative to the setback member 9and therefore also relative to the dose stop member 7, the dose stopmember 7 is caused to slide in the distal direction by a distancecorresponding to the set dose due to its engagement with the threads 24in the dose set knob 2.

During injection, because the setback member 9 and the dose set knob 2are rotationally coupled as discussed above, the dose stop member 7 willmaintain its position relative to the threads 24 of the dose set knob 2.The dose stop member 7 will move in the distal direction during dosesetting until a distal edge 73 of the dose stop member 7 abuts aninwardly directed key 26 provided on the internal surface of the doseset knob 2, as shown in FIGS. 14 and 16. In this position, the dose stopmember 7 is prevented from further movement in the distal directionwhich also prevents further rotation of the dose set knob 2 to set anadditional dose. In its final position, as shown in FIG. 16, the dosestop member 7 is threadedly engaged with approximately two of thedistal-most threads of threads 24 provided in the dose set knob 2. Asshown with respect to FIGS. 15 and 16, the total distance traveled bythe dose stop member 7 from its initial position to its final positionwhen it abuts key 26 provided on the dose set knob 2, is greater thanthe length of either of the thread portions 72 and 24 provided on thedose stop member 7 and the dose set knob 2, respectively.

FIGS. 20 and 21 illustrate another embodiment with similar functionalityas that described above, as apparent by the commonly assigned referencenumerals to the various components in the form of “1xx”. FIGS. 20 and 21illustrate an alternate embodiment of the dose stop member 7′, as shown.The dose stop member 107 is still a half-nut like element but iselongated with a greater number of threads 172. The dose stop member 107is also now threadedly engaged with only a single ¾ length thread 129provided on the interior of the dose set knob 102. The dose stop memberstill slides in the distal direction relative to the setback member 109in the same manner as above until it abuts the key 126 on the interiorof the dose set knob 102. Alternatively, the dose stop members 7 and 107can be configured to similarly slide in the proximal direction duringsetting of a dose until the dose stop members 7 and 107 abut theenlarged portions 91 and 191 near the proximal end of the setbackmembers 9 and 109, respectively, thus preventing further setting of adose that would exceed the amount of medication remaining in thecartridges 15 and 115.

FIGS. 22-28 illustrate a third exemplary embodiment of an injection pen200 with similar functionality to the above exemplary embodiments. Likereference numerals have been included where the depicted components aresubstantially the same in the form “2xx”. Each of the components of theinjection pen 200 shown in FIGS. 22-28 and its respective functionalityis substantially the same as the above exemplary embodiments unlessdescribed otherwise.

The exemplary embodiment depicted in FIGS. 22-28 includes an additionalelement referred to as the brake tower core 220. The brake tower core220 is surrounded by the brake tower 205 and is provided axially androtationally fixed to the brake tower 205. As shown in FIG. 24, thebrake tower core 220 includes a plurality of teeth 222 provided on anenlarged surface 223 near the proximal end thereof. The plurality ofteeth 222 preferably extend axially toward a distal end. The pluralityof teeth 222 are configured to engage corresponding teeth 215 providedat a proximal end of the brake tower 205. The corresponding toothengagement prevents relative rotation between the brake tower core 220and the brake tower 205. The brake tower 205 is both axially androtationally fixed to the pen upper body 201 in the same mannerdescribed above. As shown, the brake tower core 220 is a substantiallycylindrical element with an open side 224 extending along an axiallength of the brake tower core 220, as shown in FIG. 24. The open side224 includes approximately one-fifth to one-quarter of the circumferenceof a cross section of the brake tower core 220. The open side 224 formstwo longitudinally extending edges 225 and 226 at each end of the openside 224.

The brake tower core 220 functions to prevent rotation of the piston rod206 relative to the brake tower 205 and thus the pen upper body 201. Asshown in FIGS. 25-27, the brake tower core 220 is surrounded by a hollowpiston rod 206. The hollow piston rod 206 includes a plurality of threadsegments 262 provided along substantially the entire length of thehollow piston rod 206. Each of the thread segments 262 has a lengthsubstantially the same as the portion of the circumference of the openside 224 of the brake tower core 220. The thread segments 262 extendinwardly into the inner cavity of the hollow piston rod 206. An outersurface of the piston rod 206 includes a plurality of window segments260 that are “punched through” the surface of the piston rod 206 toprotrude into the interior thereof. The window segments 260 are providedto aid in the manufacture of the hollow piston rod 206 to help form theinner thread segments 262. The piston rod 206 is positioned with respectto the brake tower core 220 such that the thread segments 262 align withand protrude into the open surface 224 of the brake tower core, as shownin FIGS. 25 and 27. In this position, the pair of longitudinallyextending edges 225 and 226 abut the respective edges of the protrudingthread segments 262, such that the piston rod 106 is prevented fromrotating relative to the brake tower core 220.

Similar to the above exemplary embodiments, a lead screw 204 is providedin the interior of the hollow piston rod 206. A threaded portion 242 isprovided at the distal end of the lead screw 204. Threaded portion 242is configured to engage the thread segments 262 provided on the interiorof the piston rod 206. Similar to the above exemplary embodiments, thelead screw 204 is rotationally fixed to a setback member 209 such thatrotation of the setback member 209 during an injection is transferred tothe lead screw 204. Axial movement of the lead screw 204 relative to thebrake tower core 220 is prevented in the proximal direction by the leadscrew threads 204 being larger than the diameter of the opening at adistal end 230 of the brake tower core 220, as shown in FIGS. 23 and 28.Axial movement of the lead screw 204 relative to the brake tower core220 is prevented in the distal direction by a flange 229 of the leadscrew 204 engaging the enlarged portion 223 of the brake tower core 220.As such, due to the thread engagement between the threaded portion 242of the lead screw 204 and thread segments 262 on the hollow piston rod206, relative rotation of the lead screw 204 with respect to the pistonrod 206 (which is rotationally fixed to the brake tower 205) drives thepiston rod 206 axially in the distal direction inside the cartridge 215to expel medication contained therein.

FIGS. 29-37 illustrate a fourth exemplary embodiment of an injection pen300 with similar functionality to the above exemplary embodiments. Likereference numerals have been included where the depicted components aresubstantially the same in the form “3xx”. Each of the components of theinjection pen 300 shown in FIGS. 29-37 and its respective functionalityis substantially the same as the above exemplary embodiments unlessdescribed otherwise.

The exemplary embodiment depicted in FIGS. 29-37 includes a modifiedbrake tower core 320. The brake tower core 320 is surrounded by thebrake tower 305 and is provided axially and rotationally fixed to thebrake tower 305. As shown in FIG. 32, the brake tower core 320 has apair of oppositely extending arms 321 and 322 extending from a proximalend 326 thereof. Tabs 324 and 325 extend upwardly from ends of each ofthe arms 321 and 322. The arms 321 and 322 are received by V-shapednotches 353 at a proximal end 354 of the brake tower 305. The arms 321and 322 receive the disc-shaped portion 344 (FIG. 33) of the lead screw304 such that the tabs 324 and 325 abut the disc-shaped portion 344.Accordingly, the lead screw 304 is allowed to rotate with respect to thebrake tower core 320 during an injection. The brake tower 305 is bothaxially and rotationally fixed to the pen upper body 301 insubstantially the same manner described above.

As shown, the brake tower core 320 is a substantially cylindricalelement with an open side 327 extending along an axial length of thebrake tower core 320, as shown in FIG. 32. The open side 327 includesapproximately one-fifth to one-quarter of the circumference of a crosssection of the brake tower core 320. The open side 327 forms twolongitudinally extending edges 328 and 329 at each end of the open side327.

The brake tower core 320 functions to prevent rotation of the piston rod306 relative to the brake tower 305 and thus the pen upper body 301. Asshown in FIG. 35, the brake tower core 320 is surrounded by a hollowpiston rod 306. The hollow piston rod 306 has threads 342 thatpreferably extend substantially continuously along an entirety of aninner surface 367 of the piston rod 306, as shown in FIGS. 35 and 37. Atab or key 361 extends radially inwardly at a proximal end 362 of thepiston rod 306, as shown in FIG. 34. A flange 366 for engaging thestopper 316 extends outwardly from a distal end of the piston rod 306.The piston rod 306 is positioned with respect to the brake tower core320 such that the tab 361 is received in the open surface 327 of thebrake tower core, as shown in FIG. 35. In this position, the pair oflongitudinally extending edges 328 and 329 abut the respective edges 363and 364 of the tab 361, such that the piston rod 306 is prevented fromrotating relative to the brake tower core 320, thereby controllingangular orientation of the piston rod 306. The tab or key 361 is at aproximal end of the piston rod 306 to that it can remain in theslot-like opening 327 of the brake tower core 320 as the piston rod 306moves distally.

Similar to the above exemplary embodiments, a lead screw 304 is providedin the interior of the hollow piston rod 306, as shown in FIG. 35. Athreaded portion 342 is provided at the distal end of the lead screw304, as shown in FIG. 33. The threaded portion 342 is configured toengage the thread segments 362 provided on the interior of the pistonrod 306. Similar to the above exemplary embodiments, the lead screw 304is rotationally fixed to a setback member 309 such that rotation of thesetback member 309 during an injection is transferred to the lead screw304. Axial movement of the lead screw 304 relative to the brake towercore 320 is prevented in the proximal direction by the lead screwthreads 204 being larger than the diameter of the opening at a distalend 330 of the brake tower core 320, as shown in FIG. 35. Axial movementof the lead screw 304 relative to the brake tower core 320 is preventedin the distal direction by inwardly extends tabs 365 of the brake tower305 engaging a groove 345 of the lead screw 304 disposed between theenlarged portion 323 and the disc-shaped portion 344. As such, due tothe thread engagement between the threaded portion 342 of the lead screw304 and the threads 362 of the hollow piston rod 306, relative rotationof the lead screw 304 with respect to the piston rod 306 (which isrotationally fixed to the brake tower 305) drives the piston rod 306axially in the distal direction inside the cartridge 315 to expelmedication contained therein.

FIGS. 38-41 illustrate a fifth exemplary embodiment of an injection pen400 with similar functionality to the above exemplary embodiments. Likereference numerals have been included where the depicted components aresubstantially the same in the form “4xx”. Each of the components of theinjection pen 400 shown in FIGS. 38-41 and its respective functionalityis substantially the same as the above exemplary embodiments unlessdescribed otherwise.

The exemplary embodiment depicted in FIGS. 38-41 includes a furthermodified brake tower core 420. The brake tower core 420 is surrounded bythe brake tower 405 and is provided axially and rotationally fixed tothe brake tower 405. The brake tower core 420, as shown in FIGS. 39 and40, has a plurality of teeth 422 provided on an enlarged surface 423near a proximal end thereof. The plurality of teeth 422 preferablyextend axially toward a distal end. The brake tower 405 is substantiallysimilar to the brake tower 205 shown in FIG. 34 and has a plurality ofcorresponding teeth 215 provided at a proximal end 216 of the braketower 205 (FIG. 24). The engagement between the brake tower teeth 215(FIG. 34) and the brake tower core teeth 422 prevents relative rotationbetween the brake tower core 420 and the brake tower 405. The braketower 405 is both axially and rotationally fixed to the pen upper body401 in the same manner described above.

As shown in FIG. 39, the brake tower core 420 has substantially planaropposing walls 491 and 493 extending from the enlarged portion 423. Anopen side 424 is formed between the opposing walls 491 and 493 thatextends along an axial length of the brake tower core 420. The open side424 includes approximately one-fifth to one-quarter of the circumferenceof a cross section of the brake tower core 420. The open side 424 formstwo longitudinally extending edges 425 and 426 at each end of the openside 424.

The brake tower core 420 functions to prevent rotation of the piston rod406 relative to the brake tower 405 and thus the pen upper body 401. Asshown in FIGS. 38 and 40, the brake tower core 420 is surrounded by ahollow piston rod 406. The hollow piston rod 406 has threads 462 thatextend along an entirety of an inner surface thereof. A bore 381 extendsfrom a proximal end 382 to a distal end 383 of the piston rod 406.Opposite sides 384 and 385 of an opening 386 for accessing the bore 381are substantially flat, as shown in FIG. 38.

The piston rod 406 is positioned with respect to the brake tower core420 such that the planar walls 491 and 493 of the brake tower core 420are received by the flat portions 484 and 485 of the bore opening 486 ofthe piston rod 406. The lead screw 404 is inserted through the braketower core 420 such that the lead screw threads 442 engage the pistonrod threads 462 beyond a distal end 494 of the brake tower core 420.Rotation of the lead screw 404 during an injection results in axialmovement of the piston rod 406 due to the thread engagementtherebetween. The engagement between the planar walls 491 and 493 of thebrake tower core 420 and the flat portions 484 and 485 of the piston rod406 prevent rotation of the piston rod 406 relative to the brake towercore 220 during injections.

Similar to the above exemplary embodiments, the lead screw 404 isrotationally fixed to a setback member 409 such that rotation of thesetback member 409 during an injection is transferred to the lead screw404. Axial movement of the lead screw 404 relative to the brake towercore 420 is prevented in the proximal direction by the lead screwthreads 404 being larger than the diameter of the opening at a distalend 494 of the brake tower core 420, as shown in FIG. 41. Axial movementof the lead screw 404 relative to the brake tower core 420 is preventedin the distal direction by a flange 429 of the lead screw 404 engagingthe enlarged portion 423 of the brake tower core 420. As such, due tothe thread engagement between the threaded portion 442 of the lead screw404 and the threads 462 of the hollow piston rod 406, relative rotationof the lead screw 404 with respect to the piston rod 406 (which isrotationally fixed to the brake tower 405) drives the piston rod 406axially in the distal direction inside the cartridge 415 to expelmedication contained therein.

FIGS. 42-51 illustrate a sixth exemplary embodiment of an injection pen500 with similar functionality to the above exemplary embodiments. Likereference numerals have been included where the depicted components aresubstantially the same in the form “5xx”. Each of the components of theinjection pen 500 shown in FIGS. 42-51 and its respective functionalityis substantially the same as the above exemplary embodiments unlessdescribed otherwise.

As shown in FIG. 11, the lead screw 4 snaps into an interrupted ringforming a plurality of protrusions 54 on an inner surface of the braketower 5. In the sixth exemplary embodiment, a lead screw 504 has acontinuous ring 591 into which a brake tower 505 snaps as shown in FIG.42. The continuous ring 591 is a flexible member facilitating assembly,as well as resisting disassembly forces due to the continuity of thering 591.

The lead screw 504 has an external thread 542 formed at a distal end 543to engage threads of a piston rod 506, as shown in FIGS. 43 and 44. Thecontinuous ring 591 is disposed at a proximal end 544 of the lead screw504. The continuous ring 591 has an inner surface 592 and an outersurface 593. A circumferential rim 594 extends from the inner surface592 of the ring 591. The circumferential rim 594 has an angled surface595, as shown in FIG. 44, to facilitate insertion of the brake tower505.

A tower core 520 is disposed on the lead screw 504, as shown in FIG. 45.The tower core 520 has an open surface to receive the lead screw 504.The lead screw 504 and brake tower core 520 are then inserted through anopening 581 at a proximal end 583 of the brake tower 505, as shown inFIG. 46. The opening 581 at the proximal end 583 of the brake tower 505then flexes outwardly to receive the enlarged portion 523 of the braketower core 520, as shown in FIGS. 47 and 48. The lead screw 504 has notyet been connected to the brake tower 505 to allow the opening 581 atthe proximal end 583 of the brake tower 505 to decompress, therebyreducing stress thereon. The enlarged portion 523 of the brake towercore 520 is received within an internal cavity of the brake tower 505.

As shown in FIG. 49, the lead screw 504 is snap-connected to the braketower 505. Pushing the lead screw 504 in the distal direction causes theangled surface 595 of the rim 594 of the ring 591 to flex outwardlyalong an angled surface 584 at the proximal end 583 of the brake tower505. The circumferential rim 594 snaps into a recess 585 formed in anouter surface 586 of the brake tower 505 adjacent the proximal end 583thereof. The brake tower core 520 has not yet been rotationally lockedto the brake tower 505 such that the brake tower core 520 is free torotate.

As shown in FIG. 50, the piston rod 506 is inserted in the internalcavity of the brake tower 505 from a distal end thereof. The internalthreads 562 of the piston rod 506 are threaded onto the threads 542(FIG. 45) of the lead screw 504 such that the piston rod 506 is threadedin the proximal direction into the brake tower 505. The piston rod 506is threaded until a proximal end 563 of the piston rod 506 abuts theenlarged portion 523 of the brake tower core 520. The brake tower core520 is then pushed distally into the brake tower 505, thereby lockingthe brake tower core 520 to the brake tower 505. A pin (not shown) isinserted through a break 543 in the lead screw threads 542 to facilitatelocking the brake tower core 520 to the brake tower 505.

FIGS. 52-75 illustrate a seventh exemplary embodiment of an injectionpen 600 with similar functionality to the above exemplary embodiments.Like reference numerals have been included where the depicted componentsare substantially the same in the form “6xx”. Each of the components ofthe injection pen 600 shown in FIGS. 52-75 and its respectivefunctionality is substantially the same as the above exemplaryembodiments unless described otherwise.

The exemplary embodiment depicted in FIGS. 52-75 includes an additionalelement referred to as a clicker body 680, as shown in FIGS. 52 and67-70. The clicker body 680 is surrounded by the dose set knob 602, asshown in FIG. 53. An upper surface 681 of an upper ring 682 is engagedby a push button 603. A lower surface 689 of the upper ring 682 isengaged by a distal end 690 of a setback member 609. A pair of flexiblearms 683 are connected to the upper ring 682, as shown in FIGS. 67, 68and 70. A lower ring 684 is connected to the upper ring 682, as shown inFIG. 69. The lower ring 684 has a pair of flexible arms 685 connectedthereto, as shown in FIGS. 67 and 68. Hooks 686 are disposed at freeends of the upper ring flexible arms 683, and hooks 687 are disposed atfree ends of the lower ring flexible arms 687. Preferably, the slopedsurfaces of the upper ring hooks 686 and the lower ring hooks 687 forman angle of approximately 15 degrees. An opening 688 is formed in theclicker body 680 to receive the push button 603. The upper ring flexiblearm hooks 686 engage teeth 691 of the dose set knob 602, as shown inFIG. 53. The lower ring flexible arm hooks 687 engage teeth 692 of thesetback member 609.

The brake tower core 620 is surrounded by the brake tower 605 and isprovided axially and rotationally fixed to the brake tower 605. As shownin FIGS. 60 and 72-74, the brake tower core 620 has a key 623 extendingaxially at a proximal end. The key 623 is received by a V-shaped notch653 disposed at a proximal end of the brake tower 605. The key 623 hasinwardly tapering sides, as shown in FIGS. 72-74, to facilitateengagement with the V-shaped notch 653 of the brake tower 605, therebyrotationally locking the brake tower core 620 to the brake tower 605.The brake tower 605 is both axially and rotationally fixed to the penupper body 601 in the same manner described above. As shown in FIG. 60,the brake tower core 620 is a substantially cylindrical element with anopen side 624 extending along an axial length of the brake tower core620. The open side 624 includes approximately one-fifth to one-quarterof the circumference of a cross section of the brake tower core 620. Theopen side 624 forms two longitudinally extending edges 625 and 626 ateach end of the open side 624.

The brake tower core 620 functions to prevent rotation of the piston rod606 relative to the brake tower 605 and thus the pen upper body 601. Asshown in FIG. 53, the brake tower core 620 is surrounded by a hollowpiston rod 606. The hollow piston rod 606 includes internal threads 662extending along substantially an entire length of the hollow piston rod606, as shown in FIGS. 63 and 64. The piston rod 606 is positioned withrespect to the brake tower core 620 such that an internally extendingkey 661 engages the longitudinally extending edges 625 and 626, suchthat the piston rod 606 is prevented from rotating relative to the braketower core 620, as shown in FIG. 75.

Similar to the above exemplary embodiments, a lead screw 604 (FIG. 59)is provided in the interior of the hollow piston rod 606. A threadedportion 642 is provided at the distal end of the lead screw 604. Thethreaded portion 642 is configured to engage the internal threads 662 ofthe piston rod 606. Similar to the above exemplary embodiments, the leadscrew 604 is rotationally fixed to the setback member 609 such thatrotation of the setback member 609 during an injection is transferred tothe lead screw 604. The lead screw 604 is snapped into the brake towercore 620, which is snapped into the brake tower 605, as shown in FIGS.53 and 72-74. A flange 633 of the lead screw 604 is received by a groove632 (FIG. 60) of the brake tower core 620 such that a proximal end ofthe brake tower core 620 is received by an annular groove 645 of thelead screw 604 disposed between the proximal flange 646 and the flange633 spaced inwardly therefrom. A flange 644 of the brake tower core 620is received by an inwardly extending lip 665 of the brake tower 605.Axial movement of the lead screw 604 relative to the brake tower 605 isprevented in the proximal direction by the flange 644 of the brake towercore 620 abutting the inwardly extending lip 665 of the brake tower 605.Preventing proximal axial movement of the brake tower core 620 preventsproximal axial movement of the lead screw 604, which is connected by asnap-fit to the brake tower core 620. Axial movement of the lead screw604 relative to the brake tower 605 is prevented in the distal directionby a flange 646 of the lead screw 604 abutting a distal end of the braketower 605. As such, due to the thread engagement between the threadedportion 642 of the lead screw 604 and the internal threads 662 on thehollow piston rod 606, relative rotation of the lead screw 604 withrespect to the piston rod 606 (which is rotationally fixed to the braketower core 620) drives the piston rod 606 axially in the distaldirection inside the cartridge 615 to move the stopper 616 to expelmedication contained therein.

To set a dose using the injection pen 600 of the seventh exemplaryembodiment, the user rotates the knob portion of the dose set knob 602relative to the pen upper body 601. An outer surface 659 of the dose setknob 602 includes a thread 619, as shown in FIGS. 54 and 55, that is inthreaded engagement with a plurality of threads 617 provided on theinternal surface of the pen upper body 601, as shown in FIGS. 65 and 66.Accordingly, as the dose set knob 602 is rotated relative to the penupper body 601, the dose set knob 602 screws or advances a distance outof the pen upper body 601 (FIG. 3). The dose set knob 602 includes anannular shoulder or rim 621 on the interior surface thereof near theproximal end, as shown in FIG. 5. The annular shoulder 621 engages withan enlarged portion or head 699 (FIGS. 56-58) of the setback member 609,as shown in FIG. 53. The annular shoulder 621 of the dose set knob 602preferably comprises a series of teeth or ridges 622 that engage with aplurality of similarly shaped teeth or ridges 698 provided on theenlarged head 699 of the setback member 609. Preferably, the dose setknob teeth 622 and the setback member teeth 698 extend in opposite axialdirections. During dose setting, the dose set knob 602 is free to rotatewith respect to the setback member 609 in both clockwise andcounter-clockwise directions. As this occurs, the plurality of teeth orridges 622 on the dose set knob 602 slip past the teeth 698 provided onthe head portion 699 of the setback member 609, thus providing a tactilesignal or clicking noise to indicate the setting of a dosage amount. Asfurther described below, the dose set knob 602 is enabled to rotaterelative to the setback member 609 during setting due to a one-wayratchet that prevents the setback member 609 from rotating together withthe dose set knob 602 in the setting direction.

The clicker body 680 facilitates generating a tactile signal or clickingnoise during dose setting. The upper ring hooks 686 of the clicker body680 are locked to the teeth 691 (FIGS. 54 and 55) of the dose set knob602 such that the clicker body rotates with the dose set knob 602 as thedose set knob 602 advances out of the pen upper body 601. The lower ringhooks 687 slide over the teeth 692 (FIGS. 56 and 57) of the setbackmember 609. Accordingly, a tactile signal or clicking noise is generatedto indicate to the user that a dose is being set.

To correct a set dose that may have been set too high, the user simplyrotates back the dose set knob 602 in the opposite direction. Rotationof the dose set knob 602 in this direction is not transferred to thesetback member 609 due to the one-way ratchet between the setback member609 and the brake tower 605. The setback member 609 has a pair ofratchet arms 696, as shown in FIGS. 56-58. The pair of ratchet arms 696engages a plurality of splines or teeth 652 provided on the externalsurface of the brake tower 605, as shown in FIGS. 61 and 62. The ratchetarms 696 and splines or teeth 652 are configured to allow relativerotation in only one direction, namely, the direction that enablesinjection of a set dose. The friction provided between the ratchet arms696 and the teeth 652 on the brake tower 605 is greater than thefriction between the corresponding teeth 698 and 622 on the setbackmember 609 and the dose set knob 602, respectively. Thus, the dose setknob 609 can be rotated back to correct a set dose without causingrotation of the setback member 609 in this direction. Accordingly, theteeth 692 and 622 provided on the setback member 609 and dose set knob602, respectively, slip past each other to provide a clicking noiseduring dialing back of the dose, just as during normal dose setting,thereby indicating correction of the set dose.

The clicker body 680 also facilitates generating a tactile signal orclicking noise during dose correcting. The lower ring hooks 687 of theclicker body 680 are locked to the teeth 692 (FIGS. 56 and 57) of thesetback member 609 such that the clicker body 680 is rotatably locked tothe setback member 609. Rotation of the dose set knob 602 as the doseset knob 602 is advanced back into pen upper body 601 to correct thedose causes the teeth 691 (FIGS. 54 and 55) of the dose set knob 602 toslide over the lower ring hooks 687 of the clicker body 680, therebygenerating a tactile signal or clicking noise to indicate to the userthat a dose is being corrected. Accordingly, the clicker bodyfacilitates generating a tactile signal or clicking noise during bothdose setting and dose correcting.

As the dose set knob 602 screws or advances axially out of the upperbody 601 during the setting of a dose, the setback member 609 is alsocaused to move axially out of the body by a corresponding distance. Thisaxial movement is caused by the engagement between the annular shoulder621 on the dose set knob 602 pushing against the enlarged head portion699 of the setback member 609 during its movement out of the body. Oncea desired dose is set, the user pushes the push button 603 that iscoupled to the clicker ring 680 that is axially connected to the setbackmember 609. Under the force applied by the user pressing the push button603, the setback member 609 is moved into a locking or meshingengagement with the dose set knob 602 via a meshing of the respectiveteeth or ridges 698 and 622 provided on the dose set knob 602 and thesetback member 609, respectively. As the user continues to press thepush button 603, the dose set knob 602 is caused to rotate and screwback down into the pen upper body 601 via the thread engagement betweenthe thread 619 on the dose set knob 602 and the thread 617 in the penupper body 601. Rotation of the dose set knob 602 is then transferred tothe setback member 609 due to their locking or meshed engagement. Theforce of the user pressing the button 603 is enough to overcome thefriction between the ratchet arms 696 on the setback member 609 and theteeth or splines 652 on the brake tower 605. As a result, the setbackmember 609 is enabled to rotate in this direction. As the setback member609 rotates relative to the brake tower 605 during injection, theratchet arms 696 produce a tactile signal or clicking noise as theyratchet past the teeth 652 on the brake tower 605. This indicates to theuser that injection of the set dose is taking place. Because the doseset knob 602 and the setback member 609 rotate together during theinjection, the clicker body does not rotate relative to either the doseset knob 602 or the setback member 609. Accordingly, the clicker body680 rotates with both the dose set knob 602 and the setback member 609such that the clicker body 680 does not generate a tactile signal orclicking noise when injecting a set dose.

Rotation of the setback member 609, as allowed during injection, is thentransferred to the lead screw 604, which is rotatably fixed to thesetback member 609 via a key groove connection provided between the leadscrew 604 and the setback member 609. As shown in FIGS. 56 and 57, aninternal surface 668 of the setback member 609 includes a groove or slot697 that is engaged with a key 648 provided at the proximal end of thelead screw 604, as shown in FIG. 59. The setback member 609 preferablyincludes two oppositely disposed slots 697 for engaging two oppositelydisposed keys 648 provided on the lead screw 604. The setback member 609moves axially relative to the lead screw 604 during dose setting anddose correcting, via the key 648 and slot 697 interconnection(substantially similar to FIG. 10). The length of the slot 697 in thesetback member 609 may be configured to correspond to a maximum dose tobe injected in a single injection. The lead screw 604 is axially fixedwith respect to the pen upper body 601 via a snap engagement describedabove with the brake tower 605, which is axially and rotatably fixed tothe pen upper body 601 as described further below. As shown in FIGS.72-74, the lead screw 604 includes the inwardly disposed flange 633 thatis received by the recess 632 in the brake tower core 620. The flange644 of the brake tower core 620 is received by the inwardly extendinglip 665 of the brake tower 605, thereby axially locking the lead screw604 to the brake tower 605 and the pen upper body 601.

As described above, the lead screw 604 includes a plurality of threads642 at its distal end that are in threaded engagement with the internalthreads 662 preferably provided along the entire length of the hollowpiston rod 606, as shown in FIGS. 53 and 64. The piston rod 606 is heldnon-rotatable with respect to the pen upper body 601 due to theengagement between the piston rod key 661 and the outer edges 625 and626 of the brake tower core 620, as shown in FIG. 75. The piston rod key661 is guided in its axial movement by the axially extending outer edges625 and 626 of the brake tower core 620, thereby preventing relativerotation therebetween while permitting the piston rod 606 to moveaxially with respect thereto. As the setback member 609 does not rotateduring dose setting and correcting, the lead screw 604 does not rotateduring dose setting and correcting, which prevents movement of thepiston rod 606 during dose setting and correcting. Accordingly, rotationof the lead screw 604 during injection of a dose causes the threads 642of the lead screw 604 to engage the threads 662 of the piston rod 606,thereby axially moving the piston rod 606.

During assembly, the brake tower 605 is inserted into the pen upper body601 from the distal end. As shown in FIGS. 53 and 66, the pen upper body601 includes a transverse wall 660 that limits the movement of the braketower 605 into the body 601 by blocking an enlarged distal portion 666of the brake tower 605. Further, an inwardly protruding key 663 is alsoprovided distally from the transverse wall 660 on an internal surface664 of the pen upper body 601, as shown in FIG. 66. The key 663 engageswith a slot 655 provided on the enlarged distal portion 666 of the braketower 605, as shown in FIGS. 61 and 62, to rotationally fix the braketower 605 with respect to the pen upper body 601. Preferably, aplurality of axially extending keys 663 are disposed on the innersurface of the pen upper body 601 to engage a plurality of slots 655 onthe enlarged distal portion 666 of the brake tower 605.

Because the piston rod 606 is non-rotatable with respect to the body601, as the lead screw 604 is caused to rotate during injection, asdescribed above due to its rotational coupling with setback member 609,the piston rod 606 through its threaded engagement with lead screw 604is caused to move in the distal direction such that a piston rod flange618 presses against the stopper 616 provided in the medicament cartridge615, thus expelling a liquid medication therefrom. The piston rod 606 isprevented from moving in the proximal direction because the lead screw604 is rotatable in only a single direction (that which results indistal movement of the piston rod 606) due to the one-way ratchetbetween the setback member 609 and the brake tower 605. A mechanicaladvantage is preferably provided such that the dose set knob 602 movesfurther in the axial direction than the piston rod 606 during theinjection, reducing the injection force that must be applied by theuser. This is preferably accomplished by providing different pitches forthe threaded connection between the dose set knob 602 and the pen upperbody 601 and the threaded connection between the lead screw 604 and thepiston rod 606. The ratio between the thread pitches can vary dependingon the liquid medication and the expected dose volumes. For example, thepitch ratio can be 4.35:1 or 3.25:1, but is not limited thereto. Thus,accurate dosing can be ensured because the piston rod 606 maintains itsengagement with the stopper 616 between injections.

A dose stop member 607, as shown in FIG. 53, is provided for last dosemanagement, to prevent the setting of a dose that is larger than theremaining amount of medication in the cartridge 615. The dose stopmember 607 is axially slidable but rotationally fixed with respect tothe setback member 609 by being positioned between a pair of splines 694provided on the outer surface of the setback member 609. The dose stopmember 607 is a half-nut like element (FIG. 2b ) that is threaded on itsouter surface with a plurality of threads 672. These threads 672 areconfigured to engage with corresponding threads 674 provided on theinterior of the dose set knob 602, as shown in FIG. 55. During dosesetting, as the dose set knob 602 rotates relative to the setback member609, and therefore also relative to the dose stop member 607, the dosestop member 607 is caused to slide in the distal direction by a distancecorresponding to the set dose due to its engagement with the threads 674in the dose set knob 602.

During injection, because the setback member 609 and the dose set knob602 are rotationally coupled as discussed above, the dose stop member607 will maintain its position relative to the threads 674 of the doseset knob 602. The dose stop member 607 will move in the distal directionduring dose setting until a distal edge 673 of the dose stop member 607abuts an inwardly directed key 675 provided on the internal surface ofthe dose set knob 602, as shown in FIG. 55. In this position, the dosestop member 607 is prevented from further movement in the distaldirection which also prevents further rotation of the dose set knob 602to set an additional dose.

FIGS. 76-80 illustrate an eighth exemplary embodiment of an injectionpen with similar functionality to the injection pen of the seventhexemplary embodiments shown in FIGS. 52-66 and 71-75. The exemplaryembodiment depicted in FIGS. 76-80 includes a modified clicker body 751that replaces the clicker body 780 of FIGS. 52-66 and 71-75. Theremaining components and functions of the injection pen aresubstantially similar to the injection pen 600.

The clicker body 751 is substantially ring-shaped having an upper set ofteeth 752 and a lower set of teeth 753, as shown in FIGS. 76 and 77.Preferably, the upper teeth 752 have a slope that is opposite that ofthe lower teeth 753. Preferably, the sloped surfaces of the upper teeth752 and the lower teeth 753 form an angle of approximately 15 degrees.As shown in FIGS. 76 and 80, the clicker body 751 is disposed between anannular shoulder 725 of the dose set knob 702 and an enlarged portion731 of the setback member 709. A plurality of teeth 721 extend axiallyin the proximal direction from the shoulder 725 of the dose set knob702. A plurality of teeth 723 extend axially in the distal directionfrom the enlarged portion 731 of the setback member 709. A bearinginsert 708 is received in an annular groove 726 of the setback member709, as shown in FIG. 80. A push button 703 has a projection 733received by an opening 734 in the bearing insert 708. A distal skirt 735of the push button 703 is slidably received by a recess 736 adjacent aproximal end 737 of the dose set knob 702.

The clicker body 751 facilitates generating a tactile signal or clickingnoise during dose setting. The upper teeth 752 of the clicker body 751are locked to the teeth 721 (FIG. 79) of the dose set knob 702 such thatthe clicker body 751 rotates with the dose set knob 702 as the dose setknob 702 advances out of the pen upper body. The lower teeth 753 slideover the teeth 723 (FIG. 78) of the setback member 709. Accordingly, atactile signal or clicking noise is generated to indicate to the userthat a dose is being set.

The clicker body 751 also facilitates generating a tactile signal orclicking noise during dose correcting. The lower teeth 753 of theclicker body 751 are locked to the teeth 723 (FIG. 78) of the setbackmember 709 such that the clicker body 751 is rotatably locked to thesetback member 709. Rotation of the dose set knob 702 as the dose setknob 702 is advanced back into pen upper body to correct the dose causesthe teeth 721 (FIG. 79) of the dose set knob 702 to slide over the lowerteeth 753 of the clicker body 751, thereby generating a tactile signalor clicking noise to indicate to the user that a dose is beingcorrected. Accordingly, the clicker body 751 facilitates generating atactile signal or clicking noise during both dose setting and dosecorrecting.

Because the dose set knob 702 and the setback member 709 rotate togetherduring an injection, the clicker body 751 does not rotate relative toeither the dose set knob 702 or the setback member 709. Accordingly, theclicker body 751 rotates with both the dose set knob 702 and the setbackmember 709 such that the clicker body 751 does not generate a tactilesignal or clicking noise when injecting a set dose.

Referring to FIGS. 81, 82A and 82B, according to an exemplaryimplementation, dose set knob (DSK) 602 has internal threads 674comprising a “blunt” start 674-2 at the proximal end of the internalthreads 674. The distal end of the internal threads 674-1 has a planer(as in, for example 2-D plane) cut-off resulting in a sharp razer-edgefeathering of the thread form 674-3, as also illustrated in the exampleof FIG. 55. The key 675 is poisoned such that when the dose stop member607 reaches the maximum dialable dose condition as described above, thedistal end of the dose stop member 607 will impinge on the proximal endface 675-1 (cross hatched area) of the key 675, with the distal end ofthe dose stop member 607 approaching the proximal end face 675-1 of thekey 675 on a helical path dictated by the DSK 602 internal threads 674.

According to another exemplary implementation, at a condition of maximumdialable dose minus, for example 24 units (where, for example 24clicks=one full rotation of the DSK 602), the distal end of the dosestop member 607 will clear the proximal end 675-1 of the key 675 by somedistance that is less than one DSK internal thread 674 pitch, which canbe, for example, 0.050 inches.

According to yet another exemplary implementation, at the maximumdialable dose condition, the amount of overlap between the distal end ofthe dose stop member 607 and the proximal end face 675-1 of the key 675will be enough to have engagement with functional purpose (strength) toallow for pen lock-up at last dose, but the amount of overlap will beless than one DSK internal thread 674 pitch to account for the neededclearance just described.

According to yet another exemplary implementation, the “timing” of theDSK 602 internal threads 674, to dimensionally indicate where thethreads 674 are located both axially and rotationally can be importantto the timing of the end point of the does stop 607 at last doselock-up. If the threads are too far back or forward, or if the angularposition of the threads are off too much, then in one case the amount ofoverlap between the distal end of the dose stop 607 and the proximal endface 675-1 of the key 675 at last dose condition can be too small, andthe lockout holding strength (DSK dialing at last dose override torque)could fail at a low torque value. A consequence of this could be aninaccurate last dose in part due to the cartridge stopper entering thenon-linear region of the cartridge. The other failure mode would be thatthe does stop member 607 engages with the key 675 too soon, with the penlocking up 24 units or clicks too early. The consequence of this can bea pen that does not deliver the advertised total volume. Accordingly,what can be important to pen function is the distance between somereference point on the DSK 602 internal threads 674 and the proximal end675-1 of the key 675. Whether there is or is not a non-threaded gapbetween the threads 674 and the proximal end 675-1 of the key 675 is notas critical to the function of the pen with respect to last doselock-up, as long as if there is a gap, that the dose stop member 607 canproject over the gap while still maintaining some engagement with thethreads on at least the proximal end of the dose stop member 607.

Referring to FIGS. 83A, 83B, 83C and 83D, according to an exemplaryembodiment of the present disclosure, a DSK 802, such as DSK 602illustrated in FIG. 55, can be implemented with internal threads 874that run distally up to proximal end 675-1 of key 675. Such an exemplaryimplementation can allow to forego a cut out 810 (compare, for example,FIGS. 82A and 82B with FIGS. 83A and 83D), and facilitate easiermanufacturing of a DSK component. In an exemplary implementation,proximal end location 874-2 of internal threads 874 can remain as in theexample of FIG. 55. In yet another exemplary implementation of thepresent invention, the number of internal threads 874 forming a trackcan be approximately 13.25 full turns, where FIG. 83B illustratesposition of dose stop member 607 on track of internal threads 874 at adose stop starting position (first dose), and FIG. 83C illustratesposition of dose stop member 607 on track of internal threads 874 at adose stop ending position (last dose).

In another exemplary implementation, as illustrated in FIGS. 84A, 84B,and 84C, proximal end location 974-2 can be move so as to increase thenumber of turn of thread 974 (for example, by three added turns), whichmay be advantageous to enhancing the stability of dose stop member 607.In still another exemplary implementation of the present invention, thenumber of internal threads 974 forming a track can be approximately16.25 full turns, where FIG. 84B illustrates position of dose stopmember 607 on track of internal threads 974 at a dose stop startingposition (first dose), and FIG. 84C illustrates position of dose stopmember 607 on track of internal threads 974 at a dose stop endingposition (last dose).

While the present invention has been shown and described with referenceto particular illustrative embodiments, it is not to be restricted bysuch exemplary embodiments but only by the appended claims and theirequivalents. It is to be appreciated that those skilled in the art canchange or modify the exemplary embodiments without departing from thescope and spirit of the present invention, as defined in the appendedclaims and their equivalents.

What is claimed is:
 1. A medication injection pen, comprising: ahousing; a dose set knob (DSK) comprising an internal thread and aninternal key proximate to a distal end of said internal thread; and adose stop member comprising an external thread engaging said internalthread of said dose set knob, wherein rotation of said dose set knob toset a medication dose causes lateral translation of said dose stopmember with respect to said dose set knob, and when said dose set knobis rotated to a last dose setting position, said dose stop memberrotationally abuts said internal key thereby preventing furtherrotational movement of said dose set knob in a dose setting direction.2. The medication injection pen according to claim 1, wherein a distalend of said internal thread terminates at said internal key.
 3. Themedication injection pen according to claim 1, wherein a proximal end ofsaid internal thread engages at least a portion of said external threadof said dose stop member.
 4. The medication injection pen according toclaim 1, wherein a distal end of said internal thread terminates at adistance from said internal key.
 5. The medication injection penaccording to claim 4, wherein said dose knob comprises a cut outextending from a distal end of said internal thread to a proximal end ofsaid internal key.
 6. The medication injection pen according to claim 5,wherein said distal end of said internal thread comprises a planer sharprazer-edge feathering of the thread form.
 7. The medication injectionpen according to claim 1, wherein said internal key is poisoned suchthat when said dose stop member reaches a maximum dose conditiondialable by said DSK, a distal end of the dose stop member impinges on aproximal end face of said internal key, with said distal end of saiddose stop member approaching said proximal end face of said internal keyon a helical path dictated by said internal thread of said DSK.
 8. Themedication injection pen according to claim 1, further comprising adriver, wherein a dose stop member is disposed on said driver, said dosestop member moving axially on said driver during the dose setting andthe dose correcting and said dose stop member rotating with said driverduring the dose injection.